The present invention relates to a method of modifying a capacity of a logical path (a virtual path, hereinafter abbreviated as a VP) in a communication network in an asynchronous transfer mode (hereinafter abbreviated as ATM), and more particularly to a method of notifying a cross connect apparatus which changes over the virtual path in the unit of a cell of indication for modification in case of modifying the capacity of the virtual path.
In a communication network with a conventional synchronous transfer mode (hereinafter abbreviated as STM), change-over of a path has been performed by notifying all of cross connect nodes, where the path to be changed over passes through, of the change-over of the relevant path. Such notice is given by a separate control line from the path. It has been proposed that a similar method may be adopted in an ATM communication network using the STM communication network as an example. FIG. 2 shows such a method. A VP in an ATM is set between switching systems, and a VP management system usually executes modification of the VP capacity based on a VP capacity modification request from the switching system.
A switching system 20a issues a VP capacity modification request to a VP management system 10 when there is a need to modify a VP capacity to another switching system 20b. The VP management system 10 investigates a capacity of a transmission line and a VP capacity set status of a link where the VP passes through, issues admission of VP capacity modification to the switching system 20a and issues indication of modification of the VP capacity at the same time to cross connect systems 30a, 30b and 30c of the passing links if VP capacity modification is possible.
In above-described conventional example, it is required to issue indications of modification from the VP management system 10 through different lines to each of cross connect systems 30a, 30b and 30c, respectively. Since a VP is usually composed of approximately several ten links, it is required to issue indications of modification to several ten cross connects respectively.